1. Field of the Invention
This invention relates to video display apparatus, and more particularly, to method and apparatus for improving the vertical resolution of computer generated full color or grayscale video imagery.
2. Description of the Prior Art
A number of techniques have been employed in the prior art to deflect the scanning spot for a raster display. In U.S. Pat. No. 2,222,934, issued Nov. 26, 1940 to Blumlein, a system for synchronous spot wobble for both a TV transmitter and a receiver is described. Each scan line of the display is deflected by a sinusoidal deflection voltage, so that a reduced size spot is scanned in a sinusoidal pattern within the line width on the display screen, to improve detail resolution by the raster scan system. U.S. Pat. No. 3,418,519, issued Dec. 24, 1968 to Ferrier et al, describes a CRT deflection technique for character generation in which high frequency waves are superimposed on horizontal and vertical deflection coils to generate characters of a predetermined character height. In U.S. Pat. No. 3,792,196, issued Feb. 12, 1974, to Wendland, a system for increasing the number of levels of brightness for a CRT and superimposing a vertical deflection pattern for video transmitting and receiving apparatus is described. The transmitter is scanned horizontally using a meander wave shape to deflect the transmitter scan into adjacent scan lines, and the scan pattern of the transmitter is duplicated at the receiver.